The present invention relates to displacement measuring devices, and more particularly, to a low cost video system for monitoring the position of a float or similar target member associated with a flow measurement or control device.
A flow rotameter operates by allowing a gas or liquid to pass through a tube and move a float up or down proportionately to flow. The flow rate is determined by the position of the float relative to the scale on the tube. This type of flow meter is simple and inexpensive, and has been used regularly in various industries because it is also extremely reliable. Its major disadvantage is that a human is required to visually read the float position and manually record data for further evaluation or incorporation into a database system.
The basic problem associated with the flow rotameter also occurs in other circumstances where a physical target is connected to or adapted to move in a predetermined, linear direction in response to changes in a process condition. Equivalently, the target may move linearly as a result of action taken to control the process, e.g., stem displacement in the operator of a pneumatic valve.